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Transmission operations ensure the flow of electricity

Our operations reporting, coordination and maintenance efforts help keep the lights on for 30 million people in our balancing authority. 



Transmission control agreement

The terms and conditions for how the ISO and participating transmission owners will discharge their respective duties and responsibilities.


Transmission access charge (TAC)

Charges assessed, on behalf of the Participating Transmission Owner, to parties who require access to the ISO grid.

Transmission operating procedures

Transmission outage reports

All transmission outages must be reported to the ISO with a description of the cause and all remedial actions taken. Information is confidential. Access requires a valid user certificate.

Transmission availability performance report

The annual Electric Transmission Availability Reports are developed by each of the Participating Transmission Owners (PTOs) and submitted to the ISO for review. The Electric Transmission Availability Reports describe each PTO’s availability performance, improvements or degradation of line availability, and triggered tests.

Transmission register

The ISO provides limited access to the register of transmission facilities and entitlements (RTFE) to participants with a demonstrated, legitimate business need in accordance with FERC's January 24, 2003 Order in Docket No. ER03-219. RTFE information is considered critical energy infrastructure information.


Transmission maintenance procedures

Policies and procedures serve as guidelines for participating transmission owners.

Transmission Maintenance Coordination Committee

This independent committee gathers input from participating transmission owners and interested stakeholders on the ISO transmission maintenance standards, reviews proposed changes, recommends revisions to the standards, and advises the ISO vice president responsible for transmission maintenance.

  • Transmission Maintenance Coordination Committee meetings
    Quarterly meetings of a committee made up of electric utility industry experts to discuss maintenance concerns, recent improvements in maintenance and construction processes/techniques, industry best practices and vegetation management.
    • Transmission Maintenance Coordination Committee meetings 2023
    • Transmission Maintenance Coordination Committee meetings 2022

Tariffs and agreements

Participating transmission owner tariffs

Each participating transmission owner's tariffs for facilities under ISO operational control.

Participating transmission owner applications submitted

See terms and conditions for agreements between California ISO and transmission owners.

  • Citizens Sunrise Transmission LLC
  • SunZia Transmission, LLC
  • Citizens Sycamore-Penasquitos Transmission LLC
  • City of Anaheim
  • City of Azusa
  • City of Banning
  • City of Colton
  • City of Pasadena
  • City of Riverside
  • City of Vernon
  • David P. Addington
  • GridLiance West Transco LLC
  • Imperial Irrigation District
  • Morongo Transmission LLC
  • Startrans IO, LLC
  • The Nevada Hydro Company, Inc. (TNHC)
  • Trans-Bay Cable LLC
  • Trans-Elect NTD
  • Transwest Express
  • Valley Electric Association, Inc.
  • Western Area Power Administration